# Copyright 2019 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Handler used for loading bigquery data."""

from builtins import range
import datetime
import httplib2
import random
import time

from googleapiclient.errors import HttpError

from base import utils
from datastore import data_types
from google_cloud_utils import big_query
from handlers import base_handler
from libs import handler
from metrics import fuzzer_stats
from metrics import fuzzer_stats_schema
from metrics import logs

STATS_KINDS = [fuzzer_stats.JobRun, fuzzer_stats.TestcaseRun]

NUM_RETRIES = 2
RETRY_SLEEP_TIME = 5


class Handler(base_handler.Handler):
  """Cron handler for loading bigquery stats."""

  def _utc_now(self):
    """Return datetime.datetime.utcnow()."""
    return datetime.datetime.utcnow()

  def _execute_insert_request(self, request):
    """Executes a table/dataset insert request, retrying on transport errors."""
    for i in range(NUM_RETRIES + 1):
      try:
        request.execute()
        return True
      except HttpError as e:
        if e.resp.status == 409:
          # Already exists.
          return True

        logs.log_error('Failed to insert table/dataset.')
        return False
      except httplib2.HttpLib2Error:
        # Transport error.
        time.sleep(random.uniform(0, (1 << i) * RETRY_SLEEP_TIME))
        continue

    logs.log_error('Failed to insert table/dataset.')
    return False

  def _create_dataset_if_needed(self, bigquery, dataset_id):
    """Create a new dataset if necessary."""
    project_id = utils.get_application_id()
    dataset_body = {
        'datasetReference': {
            'datasetId': dataset_id,
            'projectId': project_id,
        },
    }
    dataset_insert = bigquery.datasets().insert(
        projectId=project_id, body=dataset_body)

    return self._execute_insert_request(dataset_insert)

  def _create_table_if_needed(self, bigquery, dataset_id, table_id):
    """Create a new table if needed."""
    project_id = utils.get_application_id()
    table_body = {
        'tableReference': {
            'datasetId': dataset_id,
            'projectId': project_id,
            'tableId': table_id,
        },
        'timePartitioning': {
            'type': 'DAY',
        },
    }

    table_insert = bigquery.tables().insert(
        projectId=project_id, datasetId=dataset_id, body=table_body)
    return self._execute_insert_request(table_insert)

  def _load_data(self, bigquery, fuzzer):
    """Load yesterday's stats into BigQuery."""
    project_id = utils.get_application_id()

    yesterday = (self._utc_now().date() - datetime.timedelta(days=1))
    date_string = yesterday.strftime('%Y%m%d')
    timestamp = utils.utc_date_to_timestamp(yesterday)

    dataset_id = fuzzer_stats.dataset_name(fuzzer)
    if not self._create_dataset_if_needed(bigquery, dataset_id):
      return

    for kind in STATS_KINDS:
      kind_name = kind.__name__
      table_id = kind_name
      if not self._create_table_if_needed(bigquery, dataset_id, table_id):
        continue

      if kind == fuzzer_stats.TestcaseRun:
        schema = fuzzer_stats_schema.get(fuzzer)
      else:
        schema = kind.SCHEMA

      gcs_path = fuzzer_stats.get_gcs_stats_path(kind_name, fuzzer, timestamp)
      load = {
          'destinationTable': {
              'projectId': project_id,
              'tableId': table_id + '$' + date_string,
              'datasetId': dataset_id,
          },
          'schemaUpdateOptions': ['ALLOW_FIELD_ADDITION',],
          'sourceFormat': 'NEWLINE_DELIMITED_JSON',
          'sourceUris': ['gs:/' + gcs_path + '*.json'],
          'writeDisposition': 'WRITE_TRUNCATE',
      }
      if schema is not None:
        load['schema'] = schema

      job_body = {
          'configuration': {
              'load': load,
          },
      }

      logs.log("Uploading job to BigQuery.", job_body=job_body)
      request = bigquery.jobs().insert(projectId=project_id, body=job_body)
      response = request.execute()

      # We cannot really check the response here, as the query might be still
      # running, but having a BigQuery jobId in the log would make our life
      # simpler if we ever have to manually check the status of the query.
      # See https://cloud.google.com/bigquery/docs/reference/rest/v2/jobs/query.
      logs.log('Response from BigQuery: %s' % response)

  @handler.check_cron()
  def get(self):
    """Load bigquery stats from GCS."""
    if not big_query.get_bucket():
      logs.log_error('Loading stats to BigQuery failed: missing bucket name.')
      return

    # Retrieve list of fuzzers before iterating them, since the query can expire
    # as we create the load jobs.
    bigquery_client = big_query.get_api_client()
    for fuzzer in list(data_types.Fuzzer.query()):
      logs.log('Loading stats to BigQuery for %s.' % fuzzer.name)
      self._load_data(bigquery_client, fuzzer.name)
